Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate a safe, read-only, idempotent operation, so the safety profile is covered. The description adds key behavioral context by explicitly stating it does not fetch a live webpage, clarifying the offline nature of the operation. This goes beyond annotations but isn't exhaustive; still, it effectively sets expectations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.